Touch screen devices are used in many classes of data processing systems such as smart phones, tablets, or conventional computers. Data processing systems that are part of measurement instruments are now utilizing such touch screens. However, in the case of these instruments, the touch gestures often do not have the required precision.
Most uses of touch screen devices do not require precise motion control, and hence, the lack of precision is not a major problem in these devices. For example, scrolling through a list, choosing an item, swiping from one screen to another are all touch gestures that do not require a high degree of precision.
When using touch devices to view instrumentation data users often require more precise gestures. For example, the user often wants to move markers or adjust the X or Y axis position of a trace very precisely on an oscilloscope. The accuracy of a touch gesture is limited by the size of the user's finger. The human finger is quite large in relation to the movement desired to precisely locate a marker. As such, it becomes difficult to position the marker to a specific pixel location with any accuracy. A user may get “almost there” and then overshoot significantly as friction causes their finger to move more quickly than they wish. In addition, the area covered by a finger is many pixels wide and getting an accurate placement is difficult.
Prior solutions to this problem utilize a special “mode” for precise gestures, requiring the user to select a fine or coarse selection. Switching between modes complicates the interaction with the touch screen and breaks the user's chain of thought.